Metallurgic extraction process for base metals (Cu, Zn, Pb), is made through the separation and concentration of sulfide minerals by differential floatation, and its pyrometallurgical processing. In the particular case of polymetallic complexes sulfide ores, there are some difficulties to produce individual concentrates of the desired grade, with a high recovery of base metals. Among the various proposed extraction treatments is the direct bleaching with different chemical agents, mainly under acidic conditions in a sulfate, chloride and nitrite media, among others. Likewise, roasting has been used as a pre-treatment for the acid bleaching (Prasad, 1998).
Another alternative in the mineral sulfide processing is using microorganisms for metal extraction, process commonly known as bioleaching. During the last 30 years, the bioleaching has been carried out in processes ranging from the bioleaching in mineral clamps, to the bioleaching in mechanically stirred tank-type bioreactors (Olson, 2003). The progress of this technology is due to the process economy, having certain advantages over the traditional mineral sulfide processing methods (Rawlings, 1998). Among these advantages, it can be said that the bioleaching does not require high energy amounts, compared with that used during the roasting or melting, it does not produce sulfur dioxide or other flue gases capable of generating residues, which are damaging for the environment (Rawlings, 2002).
Most of the first bioleaching researches and applications were focused on the mineral pre-treatment to release the gold contained in sulfides, “refractory” minerals to the conventional cyanidation process. In this process, the concentrates with high pyrite (FeS2) or arsenopyrite (FeAsS) contents are subjected to a bioleaching pre-treatment, by using bacteria in mechanically stirred tank-type bioreactors to enhance the oxidation of these “refractory” gold carrying sulfides (Ehrlich, 1997; Olson, 2003).
On the other hand, oxidation of mineral sulfides in bioleaching processes is extremely exothermic; and therefore, the bioreactor requires a severe temperature control. If temperature is not dully controlled, it may result in the bacteria extinction and the stopping of the process.
Likewise, the bioreactor heat loss may provoke problems during the bioleaching process, reason why it is also very important to control any temperature reduction.
The possible heat sources or demands that may be present in the bioleaching process are the following:                Reaction heat by the mineral sulfide oxidation.        Heat generated by absorption of the stirring power.        Heat lost by the mineral pulp heating and reactor building material.        Heat lost by the injection air expansion.        Heat lost by water evaporation by the air injection.        Heat lost by convection and radiation.        
In order to compensate the heat generation and/or loss in the bioreactor, and to maintain the temperature, it is necessary to supply the bioreactor with heating or cooling, as necessary.
In addition, due to the increasing environmental restrictions in most industrialized countries, a hydrometallurgical alternative to the pyrometallurgical treatment of sulfide concentrates mainly containing primary sulfides, such as galena (PbS), pseudogalena (ZnS) and chalcopyrite (CuFeS2), has been searched. However, industrial applications for hydrometallurgical treatment of polymetallic sulfide admixed concentrates (bulk concentrates) are scarce (Sandström, 1997; Tipre, 2004).
As mentioned above, it is possible to carry out the mineral dissolution processing, through bioleaching in mechanically stirred tank-type bioreactors (oxygen transference).
In this sense, US Patent Application No. 2008/0102514 describes a reactor and a method for the culture, solution cation biooxidation and/or the large scale propagation of isolated microorganisms pools, such as Acidithiobacillus thiooxidans Licanantay DSM 17318 in combination with Acidithiobacillus ferrooxidans Wenelen DSM 16786, with or without the presence of other native microorganisms, which are useful to bioleach metallic sulfide ores.
Likewise, in US Patent Application No. 2011/0045581, a pneumatic (air-lift) stirred bioreactor is disclosed for the continuous production of bioleaching solutions having microorganisms to inoculate and irrigate the mineral sulfides to be bioleached in clamps and bings.
In International Publication No. WO 2000/029629, a bioreactor is disclosed to carry out biooxidation processes for metal extraction from said metal-containing materials, employing a diffusor inside the reactor to maintain bacteria viability and the metal-containing material suspension, by introducing an oxygen-containing gas into a non-mechanical stirred reactor.
Finally, an operating method for a bioleaching process in a mechanically stirred tank-type reactor is disclosed in the International Publication No. WO 2006/010170. Said method includes the step of supplying non-gaseous carbon to the microbiological cells employed in the process.
As can be seen, the bioreactor use is described in the state of the art, either with mechanical or pneumatic stirring, to produce the inoculation as solution preparation for bioleaching processes in clamps. However, reactors disclosed in the prior art have the drawback of lacking of suitable gases transference, mainly oxygen. In addition, in the particular case of stirred tank-type bioreactors, its use results in microorganisms shear, affecting the viability thereof.
Thus, a bioreactor developing has been looked for, to overcome the drawbacks found in the state of the art, providing a highly efficient gas transference during the bioleaching process.